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lniteb tstta datent @ffies P. H.' VANDER WEYDE, OF PHLADELPHIA, PENNSYLVANUL Letters Patent No. 62,097, dated February 1'2, 1867; antedatef January 30, 1857.

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TO ALL Wl-IQM IT MAY CONCERN:

4Be it known that I, P. VANDER WEYDE, M. D., of l?hiladelphia, State `cf Pennsylvania, have invented an Improvement in the Mannacturing of White Lead by the wet process.

The nature of my inven'on consists in the production of the acetic and carbonio acid in succession by the same apparatus, which acids'tre wanted for the conversion of the carbonated load ores into pure white lead.

The acetic acid commonly used in this process is produced by the distillation of Wood. I also obtain it as one of the products of this distillation, but use the fractionalfcondenser, fon'fwhieh a. patent was led by the applicant January 21, 1866, and afterwards granted, September 11, No. 58,005. By this apparatus the different products of the distillation a'ro' obtained'at one single operatiombeing condensed according to their dill'erent vola.- tility; the least volatile beingcondensed first in the upper part of the coil and separated, themore volatile later, and the most volatile of all will-only come out at 'the end of the coil. This separation will take place somewhat according-to the higher or lower boiling point of the different -substances, not perfectly, it is true, but suficiently pure for many practical purposes; about in the following order: at theupper part of the coil will condense the picamar, of which the boiling point is 518 F.; next naphthalinof which the boiling point is 428 F.; next creosote and capuomore, if which the boiling point is 390 F.; next proxanthogen, of which the boiling point is 270 F.; next acetic acid, cf which the` boiling point is 248 F.; next eupione and wood spirit, of which the boiling point is'OBi F.; next wood spirit, of which the boiling point is 170 F. The chief object being to obtain the acetic acid separated from the heavier products, as creosote, 5to., the greater portion of the repeated distillations necessary in the old way of proceeding is avoided, Aparts of the acetic acid here obtained ,being at once adapted to our purpose.

The principal part of my invention, however, consists in the production of carbonio acid at the end of the same operation, this carbonio acid being necessary to precipitate the lead from the acetate of lead solution as a carbonate; it is important to have a cheap and abundant supply. I obtain this supply by blowing air in the bottom of the still as soon as all the volatile products of the wood have been drive'n oi` and nothing but the charcoal left. This coal possessing at the end of the operation a high temperature, nothing is uecessary but toforce a current of air through to combine it with the oxygen, in fact, burn it slowly, to obtain an abundant jot oi'v carbonio acid from the top of the still, mixed with. the nitrogen of the air, which, however, is harmless in this operation. This jet is simply passed through the acetate of lead solution to precipitate the white lead.

In order to enable those acquainted with similar operations to bring my invention into practice, I give here a full description of. the apparatus represented in the adjoined drawing. v

A, Figure 1, is the still, ina vertical section, of which a, Figure 2, is the horizontal section. It is filled with wood, and difl'ersin nothing from an ordinary still but in a few tubes, b b, at the bottom provided with stop-cocks, through which air may be blown in the wood after all the volatile parts have been driven off by distillation, and another tube, c, :it the top, through which the resulting carbonio acid may be discharged in the acetate of lead solution. As this gas comes out quite hot it may be blown through a cooling coil not represented in the drawing, and passed through water to deprive it of ashes mechanically carried along with the blast, or it may be discharged through the condensing coil D, and brought by the tube l m n p in the acetate of lead solution. D is the fractional condenser described in my patent of January 21, 1866, only diering from it that the last exit tube e, for uncondensable gases, leads in the furnace, where they burn, thus eeonomizing fuel, and even maybe sulcicnt toma-part of the distillation. F is the vessel containing the A acetate oflead solution, which by {ilteringfhas been-'separated from the insoluble impurities of the one. For this filtering my percolator and filtering -machine G, patented April 10, 1866, may be advantageously employed. To heep the gas longer in contact with the solution than would be the case when simply blowing it through it passes upward along the under side of an inverted gutter, It h, wound spirally. To improve the opacity of the precipitate, it may be treated with pure quicklimeand water or somc`other alkaline solution.

What I'claim, and wish to scc-ure by Letters of Patent, is

1. To ecct with the same apparatus, und one single operation, the separation of the products of the distillation of wood, chielly of theacetic acid, the immediate transformation of the remaining charcoal into carbonio acid, and the use of those two products to the manufacturing of white lead in the incliner described.

2. The spiral inverted gutter h h, intended either to secure a more perfect absorption of the carbonic acid or any otherv gas by the liquid, or to charge air or gas more perfectly with the vapor of the liqul through which it passes. I

3, rEhe treatment of the precipitate with a hot alkaline solution of quicklime, or 'its equivalent, and the` washing out of the filters with lime-water.

In testimony whereof -I have signed my name to this specification in the presence of two subscribing witnesses.

P. H. VANDER WEYDE.

Witnesses:

A. L. FLEURY, LOUIS DE RINCENAY. 

